The present invention relates to a disk array apparatus including: a disk drive for storing data provided by an information processor; and cache memory for temporarily storing the data thus stored in the disk drive, and a power backup method for such a disk array apparatus.
A disk array apparatus, i.e., a magnetic disk apparatus, has been conventionally in a cabinet structure. This is mainly for accommodating more magnetic disk modules, and increasing the packaging density thereof. In such a conventional magnetic disk apparatus, power supply is individually provided to a plurality of directors from a plurality of batteries provided specifically therefor. With respect to a plurality of magnetic disk modules to be accessed all together by the directors, power is also supplied from a battery provided specifically therefor. Then, power supply from the batteries is separately controlled by a power controller depending on the operation state of the corresponding components, i.e., the directors and the magnetic disk modules. As an example is described in PCT Published application WO93/24878.
In recent years, for storage devices exemplified by a storage system including a disk array apparatus as a component, various types of power backup technology have been developed. This is for the purpose of keeping data integrity, i.e., stopping losing data that is temporarily stored in a volatile memory device such as cache memory even if commercial power is interrupted for a limited time. This is a responsive answer against users' increasing demand for storage devices with such higher value properties as higher performance, advanced capability, higher reliability, higher energy efficiency, less space occupation, and others. The issue here is that, even with such technology development, there still remain some problems. That is, not to cause power supply for the storage device to abruptly stop due to temporary interruption of commercial power, users have found it difficult to make an investment to provide redundancy to their power supply systems or to make a space in the power supply systems available for such redundancy provision.